"John S" wrote in message ...

On 8/9/2015 12:23 PM, Wayne wrote:
I was looking at a MFJ remote antenna tuner, and it is specified as
being able to match 12 to 1600 ohms.

What does that mean? At 12 ohms the SWR would be about 4.2:1 and at
1600 ohms a SWR of about 32:1.

If one started from 1600 ohms around a Smith chart, the circle would
intersect at the other side at about 0.64 ohms.

Likewise starting at 12 ohms and going halfway around the chart would
end up at 210 ohms, not 1600.

How does one use the specs if the antenna to be matched has a complex
impedance? Look at the internal tuner component ranges?

# What antenna are you thinking to match?

My yard is very difficult for getting antennas up. I currently use a
vertical on 20-10 that is mounted on top of a rather large metal patio
cover.
The cover does have AC voltage available for patio lights/fans/bird bath
pump and such. So I could power a remote tuner separate from the coax if
required.

The current antenna for 20-10 is a 14.5 foot vertical, fed with a short run
of good coax and tuned at the rig end of the coax.

IIRC, the swr is about 6:1 on 20 meters, dips around 18 MHz and rises to
about 20:1 on 10 meters.
For 20:1 the charts say I will lose not more than 3 db with the short run of
coax, which is acceptable.

In practice, the antenna is performing well enough for me to leave it alone.
.....but you know how hams are.....